By now, importing books to China gives you tight restrictions, they will conduct thorough verification and evaluation of the book to see if does not violates any law specially national security. Even if the books is consider educational, all must go in one protocol. To get pass through it however, you have to use digital prints of your books to avoid any confusion and concealing any codes that represents any threats. For digital prints books, you can check samples at http://www.digitekprinting.com/digital-color-copies.